From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 8/9] arm64: head.S: use ordinary stack frame for __primary_switched()
Date: Wed, 24 Aug 2016 16:36:05 +0200 [thread overview]
Message-ID: <1472049366-10922-9-git-send-email-ard.biesheuvel@linaro.org> (raw)
In-Reply-To: <1472049366-10922-1-git-send-email-ard.biesheuvel@linaro.org>
Instead of stashing the value of the link register in x28 before setting
up the stack and calling into C code, create an ordinary PCS compatible
stack frame so that we can push the return address onto the stack.
Since exception handlers require a stack as well, assign the stach pointer
register before installing the vector table.
Note that this accounts for the difference between THREAD_START_SP and
THREAD_SIZE, given that the stack pointer is always decremented before
calling into any C code.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm64/kernel/head.S | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 27f51272de68..ad1dc61d67ac 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -415,13 +415,18 @@ ENDPROC(__create_page_tables)
*
* x0 = __PHYS_OFFSET
*/
- .set initial_sp, init_thread_union + THREAD_START_SP
__primary_switched:
- mov x28, lr // preserve LR
+ adrp x4, init_thread_union
+ add sp, x4, #THREAD_SIZE
+ msr sp_el0, x4 // Save thread_info
+
adr_l x8, vectors // load VBAR_EL1 with virtual
msr vbar_el1, x8 // vector table address
isb
+ stp xzr, x30, [sp, #-16]!
+ mov x29, sp
+
str_l x21, __fdt_pointer, x5 // Save FDT pointer
ldr_l x4, kimage_vaddr // Save the offset between
@@ -436,11 +441,6 @@ __primary_switched:
bl __pi_memset
dsb ishst // Make zero page visible to PTW
- adr_l sp, initial_sp, x4
- mov x4, sp
- and x4, x4, #~(THREAD_SIZE - 1)
- msr sp_el0, x4 // Save thread_info
- mov x29, #0
#ifdef CONFIG_KASAN
bl kasan_early_init
#endif
@@ -452,8 +452,8 @@ __primary_switched:
bl kaslr_early_init // parse FDT for KASLR options
cbz x0, 0f // KASLR disabled? just proceed
orr x23, x23, x0 // record KASLR offset
- ret x28 // we must enable KASLR, return
- // to __primary_switch()
+ ldp x29, x30, [sp], #16 // we must enable KASLR, return
+ ret // to __primary_switch()
0:
#endif
b start_kernel
--
2.7.4
next prev parent reply other threads:[~2016-08-24 14:36 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-24 14:35 [PATCH v2 0/9] arm64: clean up early boot function calls Ard Biesheuvel
2016-08-24 14:35 ` [PATCH v2 1/9] arm64: kernel: get rid of x25 and x26 with 'global' scope Ard Biesheuvel
2016-08-24 14:35 ` [PATCH v2 2/9] arm64: kernel: fix style issues in sleep.S Ard Biesheuvel
2016-08-24 16:13 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 3/9] arm64: kernel: use ordinary return/argument register for el2_setup() Ard Biesheuvel
2016-08-24 16:20 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 4/9] arm64: head.S: move KASLR processing out of __enable_mmu() Ard Biesheuvel
2016-08-24 20:36 ` Mark Rutland
2016-08-24 20:44 ` Ard Biesheuvel
2016-08-24 20:46 ` Mark Rutland
2016-08-25 13:59 ` Ard Biesheuvel
2016-08-30 10:24 ` Mark Rutland
2016-08-30 13:45 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 5/9] arm64: kernel: use x30 for __enable_mmu return address Ard Biesheuvel
2016-08-24 14:36 ` [PATCH v2 6/9] arm64: call __enable_mmu as an ordinary function for secondary/resume Ard Biesheuvel
2016-08-30 14:07 ` Mark Rutland
2016-08-24 14:36 ` [PATCH v2 7/9] arm64: kernel: drop use of x24 from primary boot path Ard Biesheuvel
2016-08-30 14:26 ` Mark Rutland
2016-08-24 14:36 ` Ard Biesheuvel [this message]
2016-08-30 14:38 ` [PATCH v2 8/9] arm64: head.S: use ordinary stack frame for __primary_switched() Mark Rutland
2016-08-24 14:36 ` [PATCH v2 9/9] arm64: head.S: document the use of callee saved registers Ard Biesheuvel
2016-08-30 14:43 ` Mark Rutland
2016-08-30 14:48 ` [PATCH v2 0/9] arm64: clean up early boot function calls Mark Rutland
2016-08-30 14:50 ` Ard Biesheuvel
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